Study of the Safety and Immunogenicity of Catch-up Vaccination With a 21-valent Pneumococcal Conjugate Vaccine (PCV21) in Healthy Infants, Toddlers, Children, and Adolescents

Inclusion Criteria: AGE * Aged 7 months to 17 years on the day of inclusion TYPE OF PARTICIPANT AND DISEASE CHARACTERISTICS * Participants who are healthy as determined by medical evaluation including medical history and physical examination For infants (7 to 11 MoA) and toddlers (12 to 23 MoA) only * Born at full term of pregnancy (≥ 37 weeks) and with a birth weight ≥ 2.5 kg or born after a gestation period above 28 (\> 28 weeks) through 36 weeks with a birth weight ≥ 1.5 kg, and in both cases medically stable as assessed by the investigator SEX, CONTRACEPTIVE/BARRIER METHOD AND PREGNANCY TESTING REQUIREMENTS For adolescents (6 to 17 YoA) only * A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies: * Is of non-childbearing potential. To be considered of non-childbearing potential, a female must be pre-menarche or surgically sterile. OR * Is of childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks prior to the study vaccine administration until at least 4 weeks after the study vaccine administration. A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) within 25 hours of before the first dose of study vaccine. INFORMED CONSENT * Assent form has been signed and dated by the participant (based on local regulations), and if applicable, and …